Quantum yields of active oxidative species formed on TiO2 photocatalyst

The quantum yield of hydroxyl radical (⋅OH) production during TiO2 photocatalysis was estimated to be 7×10−5 in aqueous solution by means of a method using terephthalic acid as a fluorescence probe. This value is much lower than the quantum yield of ordinary photocatalytic reactions (∼10−2). Conversely, the quantum yield of hole generation estimated by iodide ion oxidation was equivalent (5.7×10−2) to that of ordinary photocatalytic reactions. This implies that oxidative reactions on TiO2 photocatalyst occur mainly via photogenerated holes, not via ⋅OH.